Datalogic AMT58 Series, Manual

Page: 260 / 435

80
AMT58...PN
CHAPTER 12
MEDIA REDUNDANCY PROTOCOL
(MRP)
MRP (Media Redundancy Protocol) is a redundancy protocol supported by all Profinet
capable devices that will allow a network to be configured in a ring topology. It is stan -
dardized by the International Electrotechnical Commission as IEC 62439-2. It is suitable
to most Industrial Ethernet applications. Since Profinet is an open standard, this means
that MRP is a manufacturer independent protocol and can be used to form a ring with
devices from different manufacturers (so long as all devices are fully IEC 62439-2 com -
pliant).
It allows rings of Ethernet devices to overcome any single failure with recovery time
much faster than achievable with Spanning Tree Protocol. In other words, it allows to
prevent interruptions in an automation machine caused by a defect of a cable or a
device. In an MRP ring, the ring manager is named Media Redundancy Manager
(MRM)
, while ring clients are named
Media Redundancy Clients (MRCs)
. Any MRC is
connected to the MRM via two ways of communication. During normal work status
(network without failure in the ring) the telegrams will only be sent via one way of com -
munication; the second way of communication will be blocked by the MRM. If a failure
in the ring occurs (for instance because of a cable break), the second way of communi -
cation will be opened by the MRM.
Requirements are:
• all devices in the ring support MRP;
• you have complied with the rules for topology.
For complete information on the MRP please refer to the documentation provided by
Siemens.
Figure 1. Example of a ring topology with the MRP media redundancy